<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    div{
      position: absolute;
      width: 100px;
      height: 100px;
      background-color: #ccc;
    }
  </style>
</head>
<body>
  <div></div>

  <script>
    var div = document.querySelector('div')
    
    var timer = setInterval(function() {  
      if( div.offsetLeft >= 500 ) {
        clearInterval(timer)
      }

      div.style.left = div.offsetLeft + 5 + 'px'
    }, 30)

  </script>
</body>
</html>